pthread_barrier_destroy

, pthread_barrier_init

- destroy and initialize a barrier object

Synopsis

cc -mt [ flag... ] file... [ library... ]
#include <pthread.h>

int pthread_barrier_destroy(pthread_barrier_t *barrier);

int pthread_barrier_init(pthread_barrier_t *barrier,
     const pthread_barrierattr_t *restrict attr, unsigned count);

Description

The pthread_barrier_destroy() function destroys the barrier referenced by barrier and releases any resources used by the barrier. The effect of subsequent use of the barrier is undefined until the barrier is reinitialized by another call to pthread_barrier_init(). An implementation can use this function to set barrier to an invalid value. The results are undefined if pthread_barrier_destroy() is called when any thread is blocked on the barrier, or if this function is called with an uninitialized barrier.

The pthread_barrier_init() function allocates any resources required to use the barrier referenced by barrier and initializes the barrier with attributes referenced by attr. If attr is NULL, the default barrier attributes are used; the effect is the same as passing the address of a default barrier attributes object. The results are undefined if pthread_barrier_init() is called when any thread is blocked on the barrier (that is, has not returned from the pthread_barrier_wait(3C) call). The results are undefined if a barrier is used without first being initialized. The results are undefined if pthread_barrier_init() is called specifying an already initialized barrier.

The count argument specifies the number of threads that must call pthread_barrier_wait() before any of them successfully return from the call. The value specified by count must be greater than 0.

If the pthread_barrier_init() function fails, the barrier is not initialized and the contents of barrier are undefined.

Only the object referenced by barrier can be used for performing synchronization. The result of referring to copies of that object in calls to pthread_barrier_destroy() or pthread_barrier_wait() is undefined.

Return Values

Upon successful completion, these functions returns 0. Otherwise, an error number is returned to indicate the error.

Errors

The pthread_barrier_init() function will fail if:

EAGAIN

The system lacks the necessary resources to initialize another barrier.

EINVAL

The value specified by count is equal to 0.

ENOMEM

Insufficient memory exists to initialize the barrier.

The pthread_barrier_init() function may fail if:

EBUSY

The implementation has detected an attempt to destroy a barrier while it is in use (for example, while being used in a pthread_barrier_wait() call) by another thread.

EINVAL

The value specified by attr is invalid.

The pthread_barrier_destroy() function may fail if:

EBUSY

The implementation has detected an attempt to destroy a barrier while it is in use (for example, while being used in a pthread_barrier_wait() call) by another thread.

EINVAL

The value specified by barrier is invalid.

Attributes

See attributes(5) for descriptions of the following attributes:

See Also

pthread_barrier_wait(3C), attributes(5), standards(5)